With the growing preponderance of capacitive touchscreen sensor interfaces, high signal-to-noise ratios (SNRs) are required to provide reliable performance in the presence of various types of noise often encountered in environments where capacitive touchscreens are employed. Such noise sources include, but are not limited to, liquid crystal displays (LCDs), power supplies, and environmental or ambient noise. As a result, capacitive touchscreens are often driven by high voltage signals, which often necessities the use of an on-chip charge pump for high voltage generation. While they may often be manufactured at relatively low cost, many on-chip charge pump circuits generate undesired coherent noise that can interfere with touch detection.
What is needed is a touchscreen system, and method of operating such a system, that employs low-cost on-chip charge pump circuitry where undesired noise or distortion signals generated by the charge pump circuitry is minimized or eliminated.